Biomedical subjects

L Xia

Publications and source records attributed to L Xia.

At least 55 records · Page 3Linked to original sources

PubMed2000

[Effect of magnetic field on peroxidase activation and isozyme in Leymus chinensis].

This paper studied the effect of extra magnetic field and saline-alkali stress on the seedling growth of Leymus chinensis. The results showed that magnetic field treatment not only improved the seedling growth of L. chinensis, but also enhanced its saline-alkali tolerance. This treatment also increased its peroxidase(POD) activity, and induced an extra POD isozymic band on electropherogram. According to a comprehensive analysis, 300 mT and 200 mT for 10 minutes were determined as the optimum magnetic field intensity on L. chinensis seeds.

Enzyme Activation↗

PubMed2000

[Off pump coronary artery bypass grafting in 51 cases].

OBJECTIVE: To study the cost-effective minimal invasive coronary bypass surgery which decreases the complication associated with cardiopulmonary bypass, alleviates postoperative pain, and promotes recovery. METHODS: From August 1998 to November 1999, fifty-one patients underwent minimal invasive coronary bypass surgery with off pump technique. Age range was from 39 to 80 years (average 64). Thirty-five patients suffered from myocardial infarction and nine patients diabetes. Left ventricular ejection fraction was from 20%-72% (average 53%). All procedures were completed through medial sternotomy. Stabilizers of CTS, Octopus, and USSC were applied. The average graft was 2.7 per case. RESULTS: The operative mortality was 1.9%. The average ICU and hospital stay were 1.2 and 6 days, respectively. The average chest drainage and blood transfusion were 415 ml and 160 ml, respectively. Fifty patients survived from surgery. All survived patients had no symptoms of angina during the short-term follow-up (1 to 8 months). Two patients were followed up by postoperative coronary angiography, which showed a satisfactory anastomosis rate of 100%. CONCLUSIONS: Minimal invasive coronary bypass surgery is safe, cost-effective, and suitable for patients with high risk of extracorporeal circulation. It can also be used for multivessel disease.

Adult↗

PubMed2000

[An experimental study of immune mediating action of T-lymphocyte subsets on recurrent herpetic stromal keratitis].

OBJECTIVE: To investigate the role of T-lymphocyte subsets in the recurrent herpetic stromal keratitis (SK). METHODS: In a recurrent SK NIH mouse model, rat monoclonal antibodies were used to selectively deplete in vivo the CD(+)(4) and CD(+)(8) T-lymphocytes in mice, and the effects of the subsets on recurrent herpetic SK were evaluated. RESULTS: As measured by flow cytometry, in the mice treated with GK1.5, > 90% of CD(+)(4) T cells were depleted; and in the mice treated with H-35, > 95% of CD(+)(8) T cells were depleted. Depletion of CD(+)(4) T cells could halt the recurrence of SK, reduce the severity of recurrent SK and impair the delayed type hypersensitivity. In contrast, depletion of CD(+)(8) T cells had no effect on the outcome of the disease. Histopathologic examination of the recurrent SK demonstrated that the stromal inflammation in CD(+)(8) T-cell depleted and control mice was characterized by extensive lymphocyte and polymorphonuclear leukocyte infiltration, but only occasional lymphocytes were observed in CD(+)(4) T-cell depleted mice. CONCLUSION: The results provide evidence that recurrent herpetic SK represents an immunopathologic process mediated by CD(+)(4) T cells.

Animals↗

PubMed2000

[L-lactic acid fermentation by immobilized Rhizopus oryzae in a three-phase fluidized-bed].

L-lactic acid fermentation in a three-phase fluidized-bed bioreactor was studied by using immobilized Rhizopus oryzae cells with polyurethane particles as supporter. The results indicated that the immobilized cells were stable after used for 8 batches repeatedly. The rate and the yield of lactic acid fermentation with glucose as carbon source were 19.1 g h-1.L (bead)-1 and 82.5%, respectively. With the hydrolyzate of corn cob residue from xylose manufacturer by cellulase hydrolysis, the yield of lactic acid reached 71.9%.

Bioreactors↗

PubMed2000

[The clinical observation of microsurgery treatment in early glottic carcinomas].

OBJECTIVE: To improve the life quality of the patients with T1 glottic carcinomas, and obtain good vocal effect. METHODS: Twenty-two patients under shoring laryngoscope and microscope were operated by surgery and laser. The phonetic parameters and vocal cord states of preoperative and postoperative patients were evaluated and analyzed objectively. RESULTS: The three-year relapse rate was 9.0% (2/22), and the survival rate of three-year, four-year, five-year were 100%, 94.7%, 93.3% respectively. The postoperative phonetic quality was improved. CONCLUSION: Patients with early glottis carcinomas could be treated by microsurgery. The damage of normal tissue might be reduced, and the patient's life quality has been improved. This method should be used widely in clinic.

Adult↗

PubMed1999

Divergent inducible expression of P-selectin and E-selectin in mice and primates.

We used in vitro and in vivo approaches to examine whether tumor necrosis factor-alpha (TNF-alpha) and oncostatin M (OSM), cytokines that bind to distinct classes of receptors, differentially regulate expression of P- and E-selectin in murine and primate endothelial cells. In human umbilical vein endothelial cells, TNF-alpha rapidly increased mRNA for E-selectin but not P-selectin. OSM elicited little or no change in mRNA for E-selectin, but induced a delayed and prolonged increase in P-selectin mRNA. TNF-alpha and OSM did not cooperate to further enhance P- or E-selectin mRNA. Intravenous infusion of Escherichia coli, which markedly elevates plasma lipopolysaccharide and TNF-alpha, increased mRNA for E-selectin but not P-selectin in baboons. In murine bEnd.3 endothelioma cells, TNF-alpha and OSM individually and cooperatively increased mRNA and protein for both P- and E-selectin. Intravenous injection of these cytokines also individually and cooperatively increased mRNA for P- and E-selectin in mice. We conclude that the murine P- and E-selectin genes respond to both TNF-alpha and OSM, whereas the primate P- and E-selectin genes have much more specialized responses. Such differences should be considered when extrapolating the functions of P- and E-selectin in murine models of inflammation to humans.

Animals↗

PubMed1999

Identification of seven serotypes of bluetongue virus from the People's Republic of China.

Seven serotypes (1, 2, 3, 4, 12, 15 and 16) of bluetongue virus were isolated from the blood of sheep and cattle in the People's Republic of China between 1986 and 1996. Six of these viruses were isolated in Yunnan province. The sheep from which serotypes 1 and 16 were isolated showed obvious signs of bluetongue disease, whereas the cattle from which serotypes 2, 3, 4, 12 and 15 were isolated were clinically normal. Phylogenetic analyses of these viruses indicate that they are more closely related to one another, and to an Australian strain of serotype 1, than they are to prototype strains of bluetongue virus serotypes 2, 10, 11, 13 and 17 from the USA.

Animals↗

PubMed1999

Intracerebroventricular injection of interleukin-1 stimulates the release of high levels of interleukin-6 and interleukin-1 receptor antagonist into peripheral blood in the primate.

Previous studies in the rodent have shown that the cytokine IL-1 can act within the brain to influence peripheral IL-6 secretion. In order to determine if such an interaction occurs in the primate, we have compared the effects of intracerebroventricular vs. intravenous injection of IL-1beta on the release of IL-6 into the peripheral circulation of the monkey. The effects of i.c.v. IL-1beta on the release of the IL-1 receptor antagonist (IL-1ra) were studied in parallel. For comparison, we have also measured the release of both IL-6 and IL-1ra into lumbar CSF after i.c.v. IL-1beta injection. Ten ovariectomized rhesus monkeys with indwelling lateral ventricular and peripheral venous cannulae were studied. Human rIL-1beta (400 ng) was infused either i.c.v. or i.v. over 30 min and blood samples were collected for IL-6 and IL-1ra measurement by monoclonal human ELISAs. Although both i.c.v. and i.v. IL-1beta stimulated IL-6 and IL-1ra release into peripheral blood, the stimulation was much more profound after i.c.v. injection (p < 0.001). Peak IL-6 levels were 2010 +/- 590 pg/ml after i.c.v. IL-1beta compared to 243 +/- 60 pg/ml after i.v. IL-1beta. Peak IL-1ra levels were 61,310 +/- 16,190 pg/ml after i.c.v. IL-1beta compared to 18,175 +/- 4270 pg/ml after i.v. IL-1beta. There was no significant effect of an i.c.v. saline infusion on peripheral IL-6 or IL-1ra levels. In four animals, lumbar CSF was collected 7 h after i.c.v. IL-1beta injection. The mean concentration of IL-6 in CSF was 103, 570 +/- 13,780 pg/ml after i.c.v. IL-1beta vs. 224 +/- 190 pg/ml after i.c.v. saline injection; IL-1ra was 47,460 +/- 6290 pg/ml vs. 1040 +/- 550 pg/ml. As expected, both i.c.v. and i.v. IL-beta stimulated ACTH and cortisol release; the stimulation was significantly greater after i.c.v. compared to i.v. administration (p < 0.001). Thus, in the monkey, i.c.v. injection of IL-1beta stimulates the release of large amounts of IL-6 and IL-1ra into the CSF and the peripheral circulation. Both IL-6 and IL-1ra were released into the peripheral circulation to a much greater extent after i.c.v. compared to i.v. IL-1beta infusion. These studies provide further support in the primate for a mechanism by which inflammation within the brain could induce a variety of systemic responses.

Adrenocorticotropic Hormone↗

PubMed1999

Ubiquinone is reduced by lipoamide dehydrogenase and this reaction is potently stimulated by zinc.

Ubiquinol is an endogenously synthesized lipid-soluble antioxidant. Regeneration of ubiquinol from the oxidized form is essential to the maintenance of its antioxidant function. We demonstrated that lipoamide dehydrogenase can reduce ubiquinone to ubiquinol. Zinc increased the rate of the NADPH-dependent reduction more than 10-fold. The concentration ubiquinone resulting in the half-maximal rate of reduction was approximately 5 microM in the presence and 4 microM in the absence of zinc. These data may explain how ubiquinone is reduced to the active antioxidant ubiquinol, which plays such an important role in protecting against oxidative stress and lipid peroxidation.

Dihydrolipoamide Dehydrogenase↗

PubMed1999

Optical resolution of glycerin sulfides and glycerin selenides on the chiral stationary phase of cellulose-tris(3, 5-dimethylphenylcarbamate)

Cellulose-tris(3,5-dimethylphenylcarbamate) was prepared after a reported method and was coated onto an aminopropylated mesopore spherical silica gel. The final product was used as a chiral stationary phase of high performance liquid chromatography for the enantioseparation of a series of glycerin sulfides and glycerin selenides. Mixtures of hexane and 2-propanol were used as mobile phases. The effects of 2-propanol concentration in the mobile phase on the retention and resolution were investigated. Some enantiomers of the glycerin monosulfides and monoselenides could be separated satisfactorily, but none of the disulfides could be separated. The structural features of the solutes that influence chiral separation were discussed. Copyright 1999 Wiley-Liss, Inc.

Journal Article↗

PubMed1999

Family history characteristics, tumor microsatellite instability and germline MSH2 and MLH1 mutations in hereditary colorectal cancer.

Recent characterization of the molecular genetic basis of hereditary nonpolyposis colorectal cancer provides an important opportunity for identification of individuals and their families with germline mutations in mismatch repair genes. Cancer family history criteria that accurately define hereditary colorectal cancer are necessary for cost-effective testing for germline mutations in mismatch repair genes. The present report describes the results of analysis of 33 colorectal cancer cases/families that satisfy our modified family history criteria (Mount Sinai criteria) for colorectal cancer. Fourteen of these families met the more stringent Amsterdam criteria. Germline MSH2 and MLH1 mutations were identified by the reverse transcription-polymerase chain reaction and the protein truncation test, and confirmed by sequencing. Microsatellite instability analysis was performed on available tumors from affected patients. MSH2 or MLH1 mutations were detected in 8 of 14 Amsterdam criteria families and in 5 of the remaining 19 cases/families that only satisfied the Mount Sinai criteria. Three of the latter families had features of the Muir-Torre syndrome. A high level of microsatellite instability (MSI-H) was detected in almost all (16/18) colorectal cancers from individuals with MSH2 and MLH1 mutations, and infrequently (1/21) in colorectal cancer specimens from cases without detectable mutations. Families with germline MSH2 and MLH1 mutations tended to have individuals affected at younger ages and with multiple tumors. The Amsterdam criteria are useful, but not sufficient, for detecting hereditary colorectal cancer families with germline MSH2 and MLH1 mutations, since a proportion of cases and families with mutations in mismatch repair genes will be missed. Further development of cancer family history criteria are needed, using unbiased prospectively collected cases, to define more accurately those who will benefit from MSH2 and MLH1 mutation analysis.

Adaptor Proteins, Signal Transducing↗

PubMed1999

Boswellic acid acetate induces differentiation and apoptosis in leukemia cell lines.

Boswellic acid acetate (BC-4), a compound isolated from the herb Boswellia carterii Birdw., can induce differentiation and apoptosis of leukemia cells. Based on cell morphology and NBT reduction, BC-4 induced monocytic differentiation of myeloid leukemia HL-60, U937 and ML-1 cells at a dose under 12.5 microg/ml (24.2 microM). BC-4 was a potent inducer, with 90% of the cells showing morphologic changes and 80-90% of the cells showing NBT reduction. Specific and non-specific esterase were also increased by BC-4. Based on benzidine staining assay, BC-4 failed to induce erythroid leukemia DS-19 and K562 cells differentiation. In contrast to its selective differentiation effect, BC-4 strongly inhibited growth of all cell lines tested. The growth inhibition effect was dose- and time-dependent. In HL-60 cells, 20 microg/ml (38.8 microM) of BC-4 decreased viable cell number by 60% at 24 h, whereas at 3 days there was virtually no viable cells. Morphologic and DNA fragmentation analysis proved that BC-4 induced cell apoptosis. The dual apoptotic and differentiation effects of BC-4 suggest that it may be a powerful agent in the treatment of leukemia.

Antineoplastic Agents, Phytogenic↗

PubMed1999

Dietary iron overload inhibits carbon tetrachloride-induced promotion in chemical hepatocarcinogenesis: effects on cell proliferation, apoptosis, and antioxidation.

BACKGROUND/AIMS: The aim of this study was to investigate if feeding with carbonyl iron would facilitate the development of preneoplastic lesions initiated by diethylnitrosamine (DEN) and promoted by CCl4-induced liver cirrhosis. METHODS: Male Wistar rats were fed a diet with 1.25%-2.5% carbonyl iron for 23 weeks and received intragastric injections of CCl4 (1.0 or 2.0 ml/kg per week) for 13 weeks, followed by one i.p. injection of DEN (200 mg/kg), after which CCl4 was administered for 8 additional weeks. Animals were killed 48 h after the first CCl4 injection to evaluate liver necrosis, 8 weeks later to evaluate fibrosis, and 9 weeks after DEN to determine formation of glutathione S-transferase 7,7 (GST-7,7) positive foci. RESULTS: Treatment with iron counteracted the increased serum alanine aminotransferase levels and liver necrosis following CCl4 administration. Hepatic levels of reduced Q9 and alpha-tocopherol were elevated in rats treated with CCl4 and decreased in rats treated with iron compared to the controls. Fibrogenesis was not altered by iron treatment. Nine weeks after DEN initiation, the number and volume density of GST-7,7-positive foci in rats treated with CCl4 were significantly increased as compared with controls, but co-treatment with iron inhibited this increase. Apoptotic index was increased in iron-loaded livers, and labelling index (the fraction of S-phase hepatocytes) was decreased by co-treatment with iron in livers exposed to CCl4. CONCLUSION: Carbonyl iron depleted hepatic levels of antioxidants, it decreased CCl4-induced necrosis and cell proliferation, it enhanced apoptosis and did not facilitate fibrogenesis. These effects together may explain the suppression of CCl4-induced promotion after DEN initiation exerted by carbonyl iron in the present study.

Animals↗

PubMed1999

Transcriptional activation of HIV by Mycobacterium tuberculosis in human monocytes.

Recently it has been shown that infection with Mycobacterium tuberculosis increases the replication of HIV in mononuclear cells. The objective of this study was to investigate the mechanism(s) of up-regulation of HIV in primary human monocytes. Monocytes from healthy subjects were infected with HIV in vitro and then cultured with purified protein derivative (PPD) of M. tuberculosis. Culture supernatants were assessed for HIV p24 and cytokines. HIV expression was assessed by reverse transcriptase-polymerase chain reaction (RT-PCR). PPD induced HIV-infected monocytes to increased expression of HIV RNA and production of HIV p24. This effect correlated with production of tumour necrosis factor-alpha (TNF-alpha) in monocyte cultures. However, neutralizing antibody to TNF-alpha only partly abrogated the PPD-induced HIV p24 in these cultures. Also, PPD and culture filtrate of M. tuberculosis induced HIV mRNA expression. Further, using an adenovirus infection system containing an HIV long-terminal repeat (LTR) reporter plasmid, we showed that M. tuberculosis and its PPD induced HIV LTR. Therefore, the effect of M. tuberculosis and its PPD on HIV replication in monocytes is primarily one of transcriptional activation.

Cells, Cultured↗

PubMed1999

Extensive alternative splicing in the 5'-untranslated region of the rat and human neuropeptide Y Y5 receptor genes regulates receptor expression.

Neuropeptide Y (NPY) elicits a plethora of physiological effects by interacting with several distinct G protein-coupled receptors. Activation of one of these receptors, the NPY Y5 receptor, is thought to result in increased food intake, anticonvulsant effects, attenuation of opiate withdrawal, inhibition of neuronal activity, and alteration of renal function. Several alternatively spliced human and rat NPY Y5 receptor cDNAs have been isolated that use different combinations of exons in the 5'-untranslated region. The various human NPY Y5 receptor cDNAs appear to be differentially expressed in different brain regions. The level of human NPY Y5 receptor expressed transiently in COS1 cells was significantly influenced by the sequence of the 5'-untranslated region. These results indicate that alternative splicing in the 5'-untranslated region of the human and rat NPY Y5 receptor genes occurs in a tissue-specific manner and is one mechanism by which cells control the level of NPY Y5 receptor expression.

5' Untranslated Regions↗

PubMed1999

Characterization of a protein complex containing spliceosomal proteins SAPs 49, 130, 145, and 155.

SF3b is a U2 snRNP-associated protein complex essential for spliceosome assembly. Although evidence that SF3b contains the spliceosomal proteins SAPs 49, 130, 145, and 155 has accumulated, a protein-mediated association between all of these proteins has yet to be directly demonstrated. Here we report the isolation of a cDNA encoding SAP 130, which completes the cloning of the putative SF3b complex proteins. Using antibodies to SAP 130 and other putative SF3b components, we showed that SAPs 130, 145, and 155 are present in a protein complex in nuclear extracts and that these proteins associate with one another in purified U2 snRNP. Moreover, SAPs 155 and 130 interact with each other (directly or indirectly) within this complex, and SAPs 49 and 145 are known to interact directly with each other. Thus, together with prior work, our studies indicate that SAPs 49, 130, 145, and 155 are indeed components of SF3b. The Saccharomyces cerevisiae homologs of SAPs 49 and 145 are encoded by essential genes. We show here that the S. cerevisiae homologs of SAPs 130 and 155 (scSAP 130/RSE1 and scSAP 155, respectively) are also essential. Recently, the SF3b proteins were found in purified U12 snRNP, which functionally substitutes for U2 snRNP in the minor spliceosome. This high level of conservation, together with the prior observation that the SF3b proteins interact with pre-mRNA very close to the branch site, suggest that the SF3b complex plays a critical role near or at the spliceosome catalytic core.

Adaptor Proteins, Signal Transducing↗

PubMed1999

Localization of rat cathepsin K in osteoclasts and resorption pits: inhibition of bone resorption and cathepsin K-activity by peptidyl vinyl sulfones.

We have localized cathepsin K in rat osteoclasts and within exposed resorption pits by immuno-fluorescence microscopy. Intracellular staining using an antibody raised against recombinant mouse cathepsin K was vesicular and uniformly distributed throughout the cell. Confocal microscopy analysis did not reveal an accumulation of cathepsin K containing vesicles opposing the ruffled border and the resorption lacuna. Exposed resorption pits exhibited a uniform distribution of cathepsin K, and no differences were observed between the edges and the centers of the pits. The immunostaining of resorption pits with anti-cathepsin K antibodies demonstrates that the protease is secreted into the sub-osteoclastic compartment. Cathepsin K-specific inhibition using peptidyl vinyl sulfones as selective cysteine protease inactivators reduced bone resorption by 80% in a dose-dependent manner at sub-micromolar concentrations. No reduction of bone resorption was observed at those low concentrations using a potent cathepsin L, S, B-specific inhibitor. That the inhibition of bone resorption can be attributed to cathepsin K-like protease inhibition was corroborated by the selective inhibition of the osteoclastic Z-Gly-Pro-Arg-MbetaNA hydrolyzing activity by the cathepsin K, L, S, B-inhibitor, but not by the cathepsin L, B, and S inhibitor. Z-Gly-Pro-Arg-MbetaNA is efficiently hydrolyzed by cathepsin K but only poorly by cathepsins L, S, and B. On the contrary, the intracellular hydrolysis of the cathepsin B-specific substrate, Z-Arg-Arg-MbetaNA, was prevented by both types of inhibitors. The identification of cathepsin K in resorption pits and the inhibition of bone resorption and intracellular cathepsin K activity by selective vinyl sulfone inhibitors indicate the critical role of the protease in osteoclastic bone resorption.

Animals↗

PubMed1999

[The effect of sandostatin on sphincter of Oddi in acute severe pancreatitis in dogs].

OBJECTIVE: To study the pressure change of sphincter of Oddi (SO) in acute severe pancreatitis (ASP) and the effect of sandostatin on it. METHODS: Fifteen dogs were used and allocated into 2 groups: ASP untreated group and sandostatin group. The ASP model was prepared by retrograde ductal injection of a mixture of 5% taurocholic acid and autologous bile. SO manometic parameters including basal pressure (BP) and phasic contraction amplitude (PCA) were measured at each time spot before and after the preparation of ASP and after the administration of sandostatin. RESULTS: BP was obviously increased after ASP preparation and sandostatin could significantly decrease the BP of SO in ASP group but not PCA. CONCLUSION: Dysmotility of SO might play an important role in the severity and progression of ASP. Sandostatin may have beneficial effects in the treatment of ASP by decreasing BP of SO.

Acute Disease↗